Rock River Arms has built a lasting reputation for crafting top-quality firearms trusted by military, law enforcement, hunters and shooting enthusiasts across the board. Their complete upper receivers are an ideal choice for finishing a rifle build project or quickly swapping calibers on your preferred AR-15 platform. This complete upper receiver is chambered in the powerful .458 SOCOM, renowned for its devastating impact. It features a 16 inches chrome moly bull barrel fitted with an RRA Beast Brake, effectively mitigating felt recoil associated with such a potent round. The upper also includes a lightweight 13 inches aluminum free-float handguard with M-LOK slots, allowing seamless attachment of M-LOK compatible accessories such as bipods, foregrips and lights. A full-length picatinny rail atop the receiver provides optimal space for mounting optics or flip-up sights. Complete with a bolt carrier group and charging handle, this upper is ready-to be attached to any standard AR-15 lower receiver, offering both versatility and robust performance in any shooting application.